Thermoelectric modules of the Peltier type are used in applications where electric heating and cooling is desired, as disclosed, for example, in S. Beitner, U.S. Pat. Nos. 4,092,138; 4,107,934; and 4,143,711. Such thermoelectric modules comprise current carrying elements having hot and cold junctions sandwiched between a pair of flat parallel sheets, or substrates, constructed of Al.sub.2 O.sub.3, or a similar material having relatively low electrical conductivity and relatively high thermal conductivity.
The thermoelectric module is ordinarily mounted between spaced thermal conducting members having parallel planar surfaces as shown in FIG. 3 of both U.S. Pat. Nos. 4,107,934 and 4,143,711. The surfaces of the thermal conducting members are maintained in close contact with the respective substrates of the thermoelectric module. Close contact is maintained by disposing and arranging the thermal conducting elements to exert a compressive force upon the opposed faces of the substrates of the thermoelectric module. The compressive force is developed by a pair of bolts that are spaced apart a greater distance than the size of the thermoelectric module, and which operate to apply forces against members with planar surfaces that provide pressing surfaces, for contact with the substrates of the module, that are at least equal to the size of the module's substrates.
It is presently difficult to mount thermoelectric modules between thermal conducting members under compression, in the manner disclosed in the prior art because the substrates of the thermoelectric module are frangible, and when compressional forces are applied to the thermal conducting members, it is often the case that the forces are applied nonuniformly, so that there are developed regions of high pressure upon the faces of the thermoelectric module. Fracture of one or both substrates of the thermoelectric element then frequently occurs during the assembly process, or in operation in the field due to vibration, shock, and temperature changes.
There is, accordingly, need for an improved mounting that regulates the compressional forces applied to the compressing members, and which so locates the applied compressional force to insure that the resulting pressures are distributed over the substrate of the thermoelectric module.